(1) Field of the Invention
The present invention relates to a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a developer.
The term “recorded portion” used herein refers to a portion of a heat-sensitive recording material wherein a recorded image has been formed by carrying out recording from the protective layer side of the heat-sensitive recording material with a thermal head.
The term “unrecorded portion” used herein refers to a portion of the heat-sensitive recording material in which no recorded image has been formed by a thermal printer.
(2) Description of Related Art
Recording devices, in which a recording medium used is a heat-sensitive recording material comprising a heat-sensitive recording layer formed on one side of a support such as paper, synthetic paper or plastic film and containing a leuco dye, a developer and a binder, are compact, inexpensive and easy to maintain. Therefore, they are extensively used not only as a recording medium for facsimile machines, ticket-vending machines, scientific measuring instruments and so on but also as an output medium in printers or plotters for POS labels, CAD, CRT medical images or the like.
Among them, for use in image printers in CRT medical measuring instruments which require the uniformity and high resolutions of recorded images and for use in CAD plotters which require the dimensional stability and fine-line recording, synthetic papers of multi-layer structure and biaxially oriented thermoplastic resin films optionally containing an inorganic pigment are used. With an increased diversity of purposes, there is a strong demand for heat-sensitive recording materials having excellent surface gloss and recorded image quality which are comparable with those of silver-salt photographs, and having excellent recording runnability.
Japanese Unexamined Patent Publications Nos.1996-90907 and No.1997-24667 disclose heat-sensitive recording materials having an outermost layer (protective layer) transferred from a smooth surface in order to improve image clarity. However, it is desired to further improve the stability of quality and the distinctness of image of the protective layer surface.